This invention relates to condensate traps.
GB-A-2256472 discloses a condensate trap comprising a trap chamber having an outlet controlled by a valve, and a sensor chamber having an inlet, the sensor chamber communicating with the trap chamber through a first passageway, which opens into the sensor chamber at a first port in an upper region of the sensor chamber, and through a second passageway which opens into the sensor chamber at a second port situated in the sensor chamber at a lower level than the first port, a sensor being provided which has a sensor element situated within the sensor chamber at a level which is not lower than the lowest part of the second port.
The sensor chamber comprises the interior of a square cross-section tube fitted into a cylindrical cavity. The first and second ports are defined by clearances between the upper and lower ends, respectively, of the tube and the wall of the cavity. In normal operation of the condensate trap, the sensor chamber contains condensate, and so the sensor element is submerged. If leakage occurs past the valve, the resulting pressure difference causes the condensate to be forced past the lower end of the sensor tube and into the trap chamber, with the result that the sensor element is exposed to steam, and so provides an alarm signal.
A disadvantage of the device described in GB-A-2256472 is that the square cross-section tube is itself a specially manufactured component, and requires complex measures to locate its lower end. Also, the first and second passageways communicate with the trap chamber through a common port, which means that it is difficult to control the relationship between the flow cross-sections of the two passageways.